Tilley



A. E. TILLEY July 3, 1962 METHOD AND APPARATUS FOR TIMING SEISMIC RECORDINGS Original Filed May 18, 1954 Inlin- V. Ri. OL 4. E `Tw MN Ne .R E O ,VM 1 T Naf lu vu B United States Patent O 1 25,194 METHOD AND APPARATUS FOR TIMING SEISMIC RECORDIYGS Aubra E. Tilley, Fullerton, Calif., assiguor to California Research Corporation, San Francisco, Calif., a corporation of Delaware Original No. 2,803,809, dated Aug. 20, 1957, Ser. No. 430,593, May 18, 1954. Application for reissue Oct. 2, 1961, Ser. No. 146,399

4 Claims. (Cl. 340-155) Matter enclosed in heavy brackets appears in the original patent but forms no part of this reissue specification; matter printed in italics indicates the additions made by reissue.

This invention relates in general to seismic prospecting, and relates more specilically to the recording and analysis of seismic detector signals.

In the seismic prospecting art, the mechanical energy of seismic waves artificially generated in the ground is translated by means of a plurality of seismic wave detectors into electrical impulses varying in sympathy with such waves, and these impulses are amplified and recorded in some manner for analysis. It is desirable to record the resulting impulses on both a permanent record and on some type of reproducible recording medium, such as a photographic medium or a magnetizable medium, on which the desired information may be recorded and subesequently withdrawn a number of times. The reproducibly-recorded Signals may then Ibe subsequently played back and modied in a number of ydifferent Ways by changing different parameters, for comparison with the original signals. A permanent record is usually made of the resulting modified signals from the reproducible recording medium, and the resulting modified signals may also be transitorily recorded on some type of oscilloscopio display means to permit rapid visual evaluation of the elfect on the signals of variations in the dilerent parameters.

In the analysis of such records, it is essential that an accurate time reference he provided so that reilections or other events appearing on one of the records may be accurately correlated with the corresponding reflection or other events on the other records and/ or on the display medium.

Briefly, the present invention contemplates methods and apparatus for recording seismic detector signals in which the signals are recorded simultaneously on a permanent record and on a reproducible recording medium and in which an accurate common timing signal is provided on each of the records. This common timing signal is then available for use throughout the subsequent analysis of the records and the analysis of records made from the reproducibly-recorded record.

It is, therefore, an object of the present invention to provide an improved method and apparatus for recording seismic detector signals.

It is a further object of this invention to provide methods and apparatus for recording an analyzing seismic detector signals in which a common timing reference is recorded simultaneously with the seismic detector signals on a permanent record and -on a reproducible recording medium to provide a reference for subsequent time correlation of the information contained in the two reco-rds.

It is an additional object of the present invention to provide improved methods and apparatus for recording seism-ic detector signals in which a common timing reference is provided on both a permanent record and on a reproducible recording medium containing the seismic detector signals and in which the common timing reference is available for su-bsequent time correlation of the signals on the records and on records subsequently produced from the reproducible record.

Re. 25,194 Reissued July 3, 1962 Objects and advantages other than those outlined above will readily -be apparent from the following description when read in connection with the accompanying drawing the single FIGURE of which illustrates one embodiment of the present invention.

The Figure Referring to [FIG. l] by character of reference, numeral 9 designates a firing circuit or other suitable means for initiating an explosion or other source of seismic waves in the earth. A seismic detector 10 generates an electrical signal varying in sympathy with Variations in the movement of the earth in response to these seismic waves. Although, for simplicity, only one seismic detector has been illustrated, it will be obvious that in practice a considerable number of such detectors are usually used, and such detectors may be arranged in any desirable pattern or configuration.

The output signal from detector y10 is supplied to suitable amplifying means 11. The ouput of amplier 11 is supplied to means shown schematically at 8 for processing the signal in different ways prior to recording or display. Such processing may include filtering and/ or combining the signals from the diiferent detectors to produce a composite signal, as is well known in the art. The output of processing means 8 is lsupplied through a contact 13r of a selector switch `13 to a reproducible recording medium 12, such as a magnetic tape recorder having recording heads thereon for variably magnetizing the tape in accordance with variations in the signals supplied to the recording heads, and having a plurality of pickup or reproducing heads for withdrawing information from the tape.

Simultaneously with the recording of the output of means 8 on the recorder 12, the output of means 8 is also utilized to produce a permanent record of the variations in the ouput of detector `10. Such a permanent vrecord may be obtained by impressing the ouput of processing means 8 upon a suitable photographic device 15 having a camera portion 15a in which the intensity of a light source is modulated in accordance with variations in the signal from detector 10 to produce a record of such variations on a strip of photosensitive paper, vas is well known in the art. Device 15 is also provided with a portion 15b for producing a series of reference timing Vmarks on the photographic record, as will be explained more fully below. The output signal processing 'means 8 may also be supplied to suitable display means 16, such as a cathode ray oscilloscope, for displaying the seismic detector signal.

In accordance with the present invention, a source of timing signals is impressed simultaneously upon the records being made by recorder 212 and camera '15, and this common timing reference may subsequently be used t'o time accurately events occurring on the two records or on records made from the original records. In the embodiment illustrated in FIG. l, a device 20 is provided to generate a signal having a suitable shape, such as sine wave of predetermined frequency. Generator 20 may be connected to tiring circuit 9 to control the opera'tion of the generator. The output from generator 20 is supplied through the contact 25r of a selector switch 25 to a shaping circuit including a pulse Shaper 26 lWhere the sine wave is shaped into a series of pips or Spikes of negligible duration and separated from each Aother by a suitable time interval, such as 0,01 second.

The output of Shaper 26 is impressed simultaneously on a divider 2.7 and a mixer 28. Divider 27 operates to divide the number of pips lfrom Shaper 26 by a suitable integer to produce `at the output of divider 27 a series 0f pips of amplitude greater than the pips from shaper 26 and separated from each other by an interval which is :he selected integral multiple of the separation of the -)ulses from shaper 26. In a practical embodiment of :he invention, divider 27 could be ladapted to produce pips if amplitude greater than the pips -ffrom shaper 26 and separated from each other by an interval of 0.1 second.

The output Iof divider 27 is connected through the :ontact 31r of `a selector switch 31 to the input of mixer Z8, where the signals from shaper 26 and divider 27 are nixed and synchronized to produce an output consisting of a. series of pulses separated by a time interval of 0.01 second and with every tenth pulse, corresponding to a Lime interval of 0.1 second, being of a larger amplitude han the intermediate pulses.

The output from mixer 28 is impressed upon an ampliier 35 where the series -of pulses is amplified and supnlied vto component 15a of device 15. In component 15a, hese pulses modulate the light from -a suitable source to :roduce a series of timing signals on the photosensitive nedium on which the seismic ydetector signals `are re- :Iorded. Component 15a is preferably of the type prolucing a width-modulated pulse on the iilm, so that the iming signal produced on the Iilm by the pulses from nixer 28 consists of thin lines or marks every 0.01 second 1nd a wider mark at 0.1 second.

The output from mixer 218 is also impressed on the grid 38o of an amplifying tube 38 having an anode 38a ind -a cathode 38b. Anode 38a is connected to a conluctor 39 which is, in turn, connected to the positive er-m'inal of -a suitable source of plate voltage, such as a )attery 40. A resistor 41 is connected between cathode 58h and ground, and the junction of cathode 38b and 'esistor `41 is coupled through a capacitor 42 and contact I3r of -a selector switch 43 to the grid `45o of a vacuum vube 45 having an anode y45a and a cathode 45h. Anode l5a is connected through a resistor 46 to conductor 39, 1nd the common terminal of resistor 46 .and anode 45a is :onnected to a capacitor 47.

'Ilhe other terminal of capacitor 47 is connected to the grid 61c of a vacuum tube 61 having an anode 61a and 1 cathode 61fb. Tube 61 is connected for cathode folower operation with a resistor 62 connected between :athode 61h and ground. The output of this cathode :'ollower circuit is connected through a capacitor 63, a 'resistor 64, and contact `65r of a selector switch 65 to a 'ecording head of recording means 12. The output from nixer 28 is thus amplified through tubes 38, 45, and 61, rnd impressed upon a recording head of the recorder 12 o produce on the reproducible record a series of timing narks synchronized with the timing marks on the photographic record produced by device 15.

Capacitor 47 is also connected to one input terminal )f a device 5.1 yfor separating signals of dilerent amplinde. The other input terminal of device 51 is connected hrongh contact 31p of switch 31 to mixer 28, and device i1 compares the signal from mixer 28 with the signal rom tube 45 and supplies an output to display device 16, or a purpose which will be more fully explained below.

Selector switches 13, 25, 31, 42 and 65 are prefertbly ganged together for common actuation, and each :witch is provided with two operating positions. The )osition `of each of the selector switches indicated by the subscript r corresponds to the position of the switch luring recording of the seismic signals. The position )f each switch designated by the subscript p indicates he position of the switch during playback of the re- Jroducible record. Terminal 13p of switch 13 Vconnects he seismic signal output of recorder 12 to `amplifier 11, vhere the signal is amplified and supplied to signal proc- :ssing means 8. Terminal 25p of selector switch 25 :onnects the input of pulse shaper 26 through a capacitor i7 to the anode 68a of a vacuum tube 68 having a cathxde 68b and a grid 68e. Anode 68a is connected through t resistor l69 to the common plate supply conductor 39, ind cathode 68b is connected through a pair of resistors 71 and 72 to grid 68o and the commonly-connected terminals 43p and y65p of selector switches 43 and 65. Terminal 31p of selector switch 3.1 connects the output of mixer 28 to an input terminal of separator device 51.

The operation of the invention `as described above is as follows. Upon actuation of tiring circuit 9, the explosives or other source of seismic energy are activated to generates seismic waves in the earth. As shown in the drawing, generator 20` is preferably connected to tiring circuit 9 to synchronize the generator with the ring of the explosives. This synchronization may be such that the tiring, or time break, occurs at a time corresponding to generatio-n of a 0.1 second timing marker by generator 20, thereby facilitating time correlation with the time break of subsequent events on the record.

'Upon activation, generator 20 supplies to Shaper 26 a suitable signal which is shaped in Shaper 26 and impressed on divider 27 and mixer 28 to produce a series of marker pips at the output of mixer 28.

These timing pips are ampliiied by amplifier 35 and impressed on device 15b to produce a series of timing marks on the photographic record, substantially as described above. The output of mixer 28 is also impressed through tubes 38, 45, and 61 on one -channel of the reproducible recording medium 12 to produce thereon a series of timing marks synchronized with the timing marks on the photographic film. The output from detector 1I] is supplied through amplifier 11 and signal processing means 8 to recording medium 12 and photographic device 15a simultaneously with the common reference timing marks to produce on the recording medium 12 and on the lrn the timing marks and a record `of the variations of the detector signal.

To play back the recording from recording medium 12 and modify the signals thereon `for display or for producing a photo-graphic record of the modified signals, switches 13, 25, 31, 43 and 65 `are moved to the position to cl'ose their respective playback contacts 13p, 25p, 31p, 43p `and 65p. Closure of contact 65p connects the pickup head of rthe timing marks` on recording medium 12 to grid 68e of tube 68 so that the signal from this pickup head is transmitted through tube 68, capacitor 67, and cont-act 25p of selector switch 25 to shaper 26. Shaper 26 thus has supplied thereto a series of timing pulses substantially identical to those originally produced at the output of mixer 28 by the shaping circuit. The reproduced timing signals are sharpened in the shaping circuit to insure substantial i-dentity of this signal with the original timing signal generated by the circuit. Shaper 26 transmits these pulses to mixer 28, and mixer 28, in turn, supplies pulses through ampliiier 35 to component 15b of device 15 to produce on the ilm a series of timing signals synchronized with the timing signals which appeared on the film during the original recording of the seismic signals.

Mixer 28 also supplies this series of timing pulses through contact 31p of selector switch 31 to an input terminal of separator 51. Separator 51 also has supplied thereto the output voltage of tube 45, which voltage is the 'amplified timing signal from the recording medium 12. Separator 51 operates to compare the two input signals `supplied thereto in ya manner to separate the timing marks corresponding to the 0.01 second intervals, leaving only the 0.1 second marks. These 0.1 second marks are supplied to display device 16 to produce corresponding timing lines on theA display. The time interval measured by the 0.1 pulses supplied to display means 16 represents suflicient accuracy on a time scale for display purposes, since the display device is not usually used for measurements accurate beyond this interval, and additional timing lines would tend to render the displayed seismic detector signals confusing.

The recording on ydevice 12 may thu-s Ibe played back through amplifier 11 and modified in a suitable manner by signal processing device 8 to produce a permanent record in camera and/or a display of the `signals, on `device 16. All of the records produced have a common synchronous time reference, :and this Areference may be utilized to :accurately time events occurring on the records.

Although but one embodiment of the presen-t invention has been illustrated land described, it will be apparent to those skilled inthe art that vari-ous changes and modications may be m-ade therein .without departing from the spirit of the invention or the scope of the appended claim-s.

I claim:

[1. Apparatus for recording and analyzing a seismic detector signal comprising means for generating la reference timing signal, a irst recording medium, a second recording medium, means for recording said reference timing signal and said seismic detector signal on both said rst and said second recording media, means for reproducing said detector signal and said timing signal from said iii-st recording medium, means vfor modifying said reproduced seismic detector signal, and means for recording said modified seismic detector signal and said reproduced timing signal on said Second recording medium, whereby said original seismic detector signal and said modified seismic detector signal are both recorded on said second recording medium and may be compared on the basis of a common timing signal] [2. Apparatus for recording and analyzing a seismic detector signal comprising means for generating la reference timing signal, a reproducible recording medium, a photographic recording medium, means for recording -said reference timing signal Iand Said seismic detector signal on both said reproducible recording medium :and said photographic recording medium, means for reproducing said detector signal and said timing signal from said reproducible recording medium, means for modifying said reproduced seismic detector signal, and means for recording said modilied seismic detector signal and said reproduced timing signal on said photographic recording medium, whereby said original seismic detector signal and said modified seismic detector signal are both recorded on said photographic recording medium and may be `cornpared on the basis of a common timing signal] 3. Apparatus vfor recording :and analyzing a seismic detector signal comprising means for generating :an electnical voltage of constant frequency, a shaping circuit connected to said generating means for producing :a series of reference timing pulses from said vol-tage, a reproducible recording medium, a permanent recording medium, means for recording said reference timing pulses and said seismic detector signal on both .said reproducible recording medium and said permanent recording medium, means for reproducing said detector signal `and said pulses from said reproducible recording medium, signal modifying means for modifying said reproducible seismic detector sign-al, means for supplying said reproduced timing pulses to said shaping circuit to sharpen the edges of said reproduced timing pulses, land means for recording said modified seismic detector signal and said reproduced sharpened timing pulses on said permanent recording medium, whereby said original seismic detector signal and said modied seismic detector signal `are both recorded on said permanent recording medium and may be `compared on the basis of the common pulses.

4. Apparatus for multiple recording and then analyzing seismic detector signals comprising a source of seismic detector signals, signal processing means for selectively modifying said seismic detector signals, me'ans for generating an electrical voltage of constant frequency, u shaping circuit connected to said generating means for producing a series of reference timing pulses from said voltage, u reproducible recording medium, d permanent recording medium, means for originally recording said reference timing pulses und said seismic detector signals simulzuneously on both said reproducible recording medium und said permanent recording medium, means for reproducng said detector signals and said pulses from said reproducible recording medium, circuit means for supplying said reproduced seismic detector signals to said signal processing means for adjustably processing said reproduced signals, means for supplying said reproduced timing pulses to said shaping circuit to sharpen the edges of said reproduced timing pulses, and means for recording said modified seismic detector signal and said reproduced sharpened timing pulses on said permanent recording medium, whereby said originally recorded seismic 'delector signals and said modijed seismic detector signals are both recorded on said permanent recording medium and muy be aligned by comparison of said reproduced sharpened timing pulses and said originally recorded reference timing pulses.

5 Apparatus for multiple recording ondl then analyzing seismic detector signals comprising a source of seismic detector signals, signal processing means for selectively modifying said seismic detector signals, means for generutz'ng an electrical voltage of constant frequency, a shaping circuit connected to said generating means for producing u series of reference timing pulses from said voltage, u reproducible recording medium, a permanent recording medium, means for originally recording said reference timing pulses and unmodified seismic detector signals simultaneously on both said reproducible recording medium and said permanent recording medium, means for reproducing said detector signals and said pulses from said reproducible recording medium, circuit means for supplying said reproduced seismic detector signals to said signal processing means to-selectively modify said seismic detector signals, means for supplying said reproduced timing pulses to said shaping circuit to sharpen the edges of said reproduced timing pulses, and means for recording said modified seismic detector signals and said reproduced sharpened timing pulses on said permanent recording medium, whereby said originally recorded seismic detector signals and said selectively modified seismic detector signals are both recorded on said permanent recording medium and may be analyzed by alignment of said reproduced sharpened timing pulses and said originally recorded reference timing pulses.

6. Apparatus for necordz'ng and analyzing seismic detector signals comprising:

(a) a source of seismic detector signals,

(b) u source of continuous reference timing signals,

(c) a reproducible recording medium including means forreproducing signals recorded thereon,

(d) a permanent recording medium,

(e) seismic detector signal processing means including Selectable means for modifying said seismic detector signals,

(f) reference timing signal processing means for accentuatng selected timing signals from said source of continuous signals,

(g) and switching means including a plurality of groupoperated separate contacts operable to sequentially connect certain of said signals to certain of said media,

(h) first contacts of said plurality being operable to connect said seismic detector signals originally to saa reproducible and permanent recording medium and to sequentially connect seismic detector signals reproduced from` said reproducible recording medium to said permanent recording medium through said seismic detector signo! processing means,

(i) additional contacts of said plurality being operable to connect said reference timing signals originally tc said reproducible and permanent recording medium through said timing signal processing means and tc sequentially connect reference timing signals reproduced from said reproducible recording medium to said permanent recording medium without connection through said timing signal processingmeans,

(j) said rst and said additional contacts being operated at the same time to supply selectable modified seismic detector signals and reproduced original reference timing signals to said permanent recording medium for analysis with respect to said originally recorded seismic detector signals and said originally recorded reference timing signals.

References Cited in the le of this patent or the original patent UNITED STATES PATENTS Reber Sept. 16, 1947 Lee May 12, 1953 Rieber Nov. 10, 1953 Minton Mar. 23, 1954 

